Diseases Spread By Cockroaches

Cockroaches are persistent and troublesome pests of homes, restaurants, hospitals, warehouses, offices, and other structures with food handling areas. These insects contaminate food and utensils, destroy fabric and paper products, and impart stain and odor to surfaces they contact.

Cockroaches are universally loathed. One of the primary reasons is because they are associated with any place where there are biological waste products such as sewers, septic tanks, garbage cans, chicken houses, and animal cages. Their attraction to to human and animal feces, rotting food, secretions from corpses, sputum, pus, and the like gives them a well-earned "disgust factor" among the general public. All these moist, organic habitats contain staggering amounts of bacteria, protozoa, amoebae, fungi, and other microbial material.3

Cockroaches belong to the insect order Dictyoptera. Young and immature cockroaches resemble adults, that is, they undergo gradual metamorphosis. Adults of male species have wings, although many species do not fly. Although there are 70 described species of cockroaches in the United States, and over 3,500 worldwide, only a few are major pests. Occasionally species that usually occur outdoors invade buildings.

Microbes are an essential influence in the nutrition, ecology, and evolution of all cockroaches. The main source of nourishment for cockroaches in mines and sewers, for example, is human feces, which can be 80% bacterial. German cockroaches have been observed feeding on mouth secretions of corpses riddled with lung disease; these secretions were almost 100% infectious bacteria.3

The makeup of the microbial population of the American cockroach gut, long the subject of numerous investigations, has been shown to include a variety of microorganisms, bacteria, archeans, protozoa, and nematods. Cockroaches, especially species that come in contact with feces like German cockroaches may transmit bacteria responsible for food poisoning. Cockroaches act as mechanical vector in transmitting Salmonella,Shigella, and Cryptosporidium parvum bacteria that cause diarrheal diseases. Antibiotic resistant strain of Klebsiella pneumoniae bacteria that cause pneumonia has been found in patients and cockroaches in a New Delhi hospital. In addition, evidence suggests that cockroaches spread typhoid, disentery, and leprosy organisms.2

Bacteria Carried By Cockroaches

At least 32 species of bacteria have been isolated from cockroaches in domestic environments. These include:

Worms, Protozoa, Fungi, and Viruses Carried By Cockroaches

Cockroaches also have been found harboring eggs of seven species of helminths (hookworm, giant human roundworm, pinworm, tapeworm, and whipworm); at least 17 fungal species, three protozoan species, and two strains of polymyelitis virus. Australian, American, and Madeira cockroaches become infected with the protozoan Toxoplasma gondii, the causative agent of toxoplasmosis, after feeding on feces of infected cats. This suggests the possibility of cockroach involvement in the maintenance and dissemination of this parasite, which infects humans and other animals.5

At least eleven proteins isolated from German and American cockroaches can cause allergic reactions and contribute to asthma in humans. The allergens are heat-stable and persistent in the environment even after the insect death. The cockroach mite (Pimeliaphilus cunliffei) is a parasite of cockroaches. It feeds on live individuals and has been linked to bites of humans living in households with cockroach infestations.6

Exposure to cockroach allergens early in life has been associated with recurrent asthmatic wheezing in children with atopy. Control of cockroach allergen exposure may be very difficult, especially in cities. Even pesticides applied by professional exterminators are not effective. Cockroaches isolated from public hospitals have been reported to carry streptococci internally and externally, constituting a continuous source of human infection.